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S. B. KANOWITZ ET AL AND CLAY on THE LIKE Filed Oct. 6, 1920 METHOD OF SEPARATING HIGH CONTENT PHOSPHATE FROM LOW CONTENT PHOSPHATE April 28, 1925.

no n a mm 1 2 e m w a /M a w, a 2 r 9M8 m N 1. .1 N 3 ,MJ 0 9 .fl a 5 8 m 4 a m? M H 4 5 7/ a M 1 Patented Apr; 28, 1925.

UNITED STATES PATENT OFFICE.

SAMUEL B. KANOWITZ, OF GREENSBURG, PENNSYLVANIA, AND HYLEMAN A. WEB- STER, OF COLUMBIA, TENNESSEE; SAID KANOWI'IZ ASSIGNOR OF HIS RIGHT TO RAYMOND BROTHERS IMPACT PULVERIZER COMPANY, OF CHICAGO, ILLINOIS, A

CORPORATION OF ILLINOIS METHOD .OF SEPABATING HIGH-OONTENT PHOSPHATE FROM LOW-CON TENT PHOS- PHA'IE AND CLAY OR THE LIKE.

Application filed October 8, 1920. Serial No. 414,956.

To all whom it may concern:

Be it known that we, SAMUEL B.- KANowrrz and I'IYLEMAN A. VEBSTER, citizens of the United States, residing, respectively, at

l Greensburg, in the county of \Vestmoreland and State of Pennsylvania, and Columbia, county of Maury, and State of Tennessee, have invented certain new and useful Improvements in Methods of Separating High- Content Phosphate from Low-Content Phosphate and Clay or the like, of which the following is a specification.

ur invention relates to the treatment of phosphate bearing material for the production of phosphate in merchantable form, that is, the production of a phosphate rock containing a relatively high percentage of tricalcium phosphate (Ca P O I The primary object of the invention is to provide an economical and simple process of separating the phosphate rock from the clay,"

sand, and the like, with which it is mixed vin the natural state, and if necessary or de sirable, separating the rock containing a relatively high percentage of trlcalelum phosphate from rock cbntaining a lower percent age of the same. While the novel process of our invention may be used to advantage in place of the usual washing method upon the relatively high grade materials to which the washing method is, for reasons of economy, restricted, our process is utilizable to a much greater advantage upon low grade deposits, or upon the refuse material from the wash ing methods, which materials are very abundant and contain vast quantities of valuable phosphate but in such condition that it has been incapable of recovery, economically, by the methods of separation 0 heretofore employed. These materials have,

therefore, been regarded as waste.

Our invention provides a method of separating the phosphate rock from the clay, sand, etc. with which it is associated in the (high in tricalcium lower grade rock.

In the separation of phosphate from the clay, according to the method commonly used prior to our invention, the phosphate bearing rock after being mined, is passed from one settling tank to another to separate the phosphate from the clay. If in large lumps, it is put through a breaker and reduced to a convenient size before being passed through the settling tanks. Another method sometimes employed is to pass the material in a screw conveyor upwardly against a stream of water whereby the loose clay is washed down with the water and separated from the rock. The separation effected by these wet methods is only approximate. Some clay always adheres to the phosphate and, obviously, whatever clay there may be in the pores of the rock is not released or removed by the washing or settling operation on the contrary the loose, finely divided clay may be washed into and held by the crevices in the rock; consequently, the washed rock when ground is not as high in phosphate content as it would be if a more complete separation of the clay were effected. Furthermore, by these old Wet methods the phosphate that is finely crushed or pulverized in mining and by the breaker is lost, it being eliminated with the water and clay; particularly is this true when a considerable percentage of the phosphate rock is relatively soft or fine, as is often the case in some localities. When the phosphate rock, or a considerable percentage of it, is in a granular state, economical separation of the phosphate from the clay by these old methods is not possible because a large per centage of the granular phosphate will be wa'shed away with the clay.

We have discovered that the harder the phosphate bearing material, the richer it is in phosphate content.

phosphate) from the i the material is That is to say, phos- 4 natural deposits, which method is applica 95 ble, unlike the former washing methods, to materials containing the phosphate in finely divided condition. The invention also provides a method of grading the rock so as to separate the high content phosphate rock phate bearing materials may vary in two difl'erent respects: They may contain more or less clay in proportion to rock, and the rock itself may be more or less rich in tricalcium phosphate. Our method seeks 5 first to separatethe clay from the rock, and 100 second, if necessary, to provide for separation as between the high grade rock and the lower ade rock. The possibility of making this second separation, by which the rade of the rock is raised, is based upon the iscovery that a rock rich in tricalcium phosphate is harder than a rock having a lower phosphate content. The process is preferably practiced as follows: the phosphate bearing material after being mined is dried to reduce the moisture content to' a negligible quantity. The dried material is then comminuted, preferably in an enclosed space, the clay or similar relatively soft forei n matter being quickly reduced to an impa pable powder. The powdered material is then separated from the other material. This preferably is accomplished by suction and a suitable air separator, the powdered material being withdrawn from said enclosed space, the residue or phosphate rock bein the tailings.

Wlien it is desired to carry out the process further and raise the grade of the product, that is, produce a product having a higher tricalcium phosphate content, the rock from the first separation is further comminuted to reduce the soft or low content phosphate to an impalpable powder, and the hard or high content phosphate to a fine granular state, and the powdered low content phosphate is then separated from the granular high content phosphate, preferably by suction and a suitable air separator. In this manner a ery complete separation may be effected and phosphate of a very sired type.

hi h grade obtained.

The preferred method, as we now regard it, is that illustrated in the accompanying drawing, Fig. 1 of which shows diagrammatically an apparatus suitable for the purpose; Fig. 2 being a detail view of a portion of one of the separators.

Referring to the drawing, the phosphate bearing material, after being mined, is dumped into a drier 5 where the moisture content is reduced to a negligible quantity. The dried material passes from the drier through a chute 6 to a crusher 7 where it is reduced to a size suitable for feeding to a comminuter. The crushed material passes from the crusher through a chute 8 to a feed bin 9, and thence through a chute 10,. which is controlled by a gate 11, to a comminuter 12. The'comminuter 12 may be of any de- VVe prefer to employ what is known as an impact pulverizer consisting of a rapidly revolving shaft 13, mounted in the pulverizing chamber 14 and -'on which are mounted beater blades 15. Preferably mounted on top of the pulverizing chamber is an air separator 16 comprising an outer conical casing 17 and an inner conical shell 18, the bottom of the casing 17 being in direct communication with the pulverizing chamber 14 and the bottom of the shell 18 being also in direct communication with the pulverizing chamber or, if desired, provided with a discharge conduit 19 controlled by a gate 20. The sepgarator is closed at thetop by a cover 21. oth the casing 17 and the inner shell 18 are preferably cylindrical adjacent the top, the top of the cylindrical portion 22 of the inner shell being secured to the cover 21. The cylindrical portion 22 is providedwith a plurality of openings 23 which are controlled by adjustable vanes 24, the latter bein regulated by shifting mechanism 25 (see iig. 2). A duct 26 provided with an exhaust fan 27 leads from the top of the inner shell 18 to a dust collector 28, preferably of the cyclone type. A duct 29 for the return passage of air leads from the dust collector to the bottom of the pulverizing chamber 14. One side of the pulverizing chamber is provided with a transverse outlet 30 and a discharge conduit 31 for the discharge of the rock or tailings.

The operation of the apparatus described is as follows: The phosphate bearing material, after being dried and if necessary crushed (the low grade material does not ordinarily require crushing as the phosphate particles are likely to be small), is comminuted by the pulverizer 12, the clay being soft compared to the phosphate is quickly reduced to an impalpable powder. The pulverizing action may result in some of the phosphate rock being reduced to a granular state, particularly if the rock is relatively soft. The powdered material and the granular material are withdrawn from the pulverizing chamber by suction, passing upwardly in the space between the outer casing and the inner shell and being drawn into the inner shell through the openings 23. The vanes 24 are positioned tangentially with respect to an imaginery circle, the size of which may be varied by shifting the vanes. With the vanes set tangentially the currents of air will have a gyratory motion within the shell 18 with the greatest velocity at the face of the imaginary circle. The velocity and length of travel of the material laden air within the shell 18 may be regulated by manipulating the vanes 24 and the air laden with matter to be separated, may be made to travel ov r a varying path with varying degrees of velocity. When the vanes are properly positioned the powdered material or clay will be withdrawn through the duct 26 and collected in the collector 28 while the granular phospha e will fall into the bottom of the shell 18 and discharge therefrom by means of the conduit 19. The phosphate rock isthoroughly beaten by the beaters 15 and accumulates in the bottom of the chamber 12. being discharged therefrom through the outlet 30. The tailings from the air separator being in a fine granular state may be used without further grinding as a direct fertilizer, being quite high in phos-.

' phate'content. If desired, the conduit 19 may be omitted;'in which case the tailings fall back into the pulverizing chamber and discharge .with the rock. By this method all the material mined may be utilized. Sub-' stantia-lly all the clay or other similar rela-- tively soft foreign matter, including that contained in the pores of the rock, is separated from the phosphate, the foreign matter being reduced to an impalpable powder may be utilized as a filler for variouspurposes and sold at a considerable profit.

When a considerable portion of the phosphate rock is of relatively low grade, that is;

bin 33, the gates 20 and 34 being closed, and

gates 35 and 36 being opened. The material passes from the feed bin 33 to a colnminuter 37 which may be of any desired type provided it is capable of the reducing action required. We preferably employ a roll and ring milladapted to reduce extremely hard material, consisting of a plurality of roller journals 38, only one being shown in the drawing, mounted on a spider 39 secured to a vertical shaft 40. Each journal is provided with a roller 41 which bears against a bull ring-42, the material being ground between the rollers and the bull ring. An air separator 43, similar in construction to the separator 16, is mounted on top of the mill. A duct 44 provided with an exhaust fan 45 leads from the separator 43 to a dust collector 46 and a duct 47 leads from the collector 46 to the pulverizing chamber of the mill. The separator 43 is provided with a conduit 48 for the discharge of the tailings.

By means of the roller mill and the associated air separating apparatus the tailings from the pulverizer 12 may be comminuted and a further separation effected. The soft or low grade phosphate will be reduced to an impalpable powder and the hard phosphate to a fine but granular state. The powdered and granular material are withdrawn from the mill into the separator 43, a separation effected as heretofore described in connection with the separator 16, the soft or low content powdered phosphate being collected in the collector 46 and the hard high content phosphate being discharged from the separator in the form of tailings. The powdered low content phosphate collected in the collector 46 is rich enough in phosphate to be utilized as a direct fertilizer while the tailings from-the separator 43 are very high in phosphate contentand may be utilized as a base in manufacturin tilizers and for other 1ndustri'al purposes.

,If the phosphate bearing material contains only a negligible quantity of the low grade ofsoft rock,- it may be desirable to by pass the pulverizer and utilize the se arator 43 for removing the clay. For t is purpose a conduit 49 controlled by a gate 50 leads from that section of the conduit 10 above the gate 11, to the feed bin 33, in which case the gate 11, of course, is'closed. By means of the method and apparatus above described, the separation of the phos: phate from the clay and, if desired, the high content hard phosphate from the low content soft phosphate, may be carried out very various kinds of ferexpeditiously and economically. The separation is more complete than can possibly be obtained by the old settling'or washing processes heretofore used, which require considerable time and large quantities of water. The latter is an important factor, since most States have laws whereby a large percentage of the water taken from a river or lake must be returned. thereto and unpolluted. The polluted water must, therefore, be filtered or otherwise treated to purify it. Furthermore, the large bodies of polluted water used in' the settling process are good places for disease breeding insects and germs, and

therefore are detrimental to the health of the community.

Applicants method makes it possible to recover substantially all the phosphate while,

by the old wet processes, a large percentage of it was lost. That this is true is proved by thefact that it has been found profitable to employ the applicants method and apparatus in working over the old dumps of material accumulated from carrying out the old processes to recover the phosphate lost by these processes.

The term clay is used generically in the appended claims, and is intended to include all relatively soft foreign matter or gangue present in the phosphate bearing material.-

\Ve claim:

1. Method of separating phosphate from clay, which consists in comminuting the phosphate bearing material while in a dry state to reduce the clay to'a powder and the phosphate to granular form, and then separating the powdered from the granular material to recover the latter by carrying away the powdered material in a body of air.

2. Method, of separating phosphate rock having a high phosphate content from clay and rock having a lower phosphate content, which consists in comminuting the phosphate bearing material while in a dry state to reduce the soft. rock and foreign matter to a powder and the hard rock to granular form, and then effecting a separation of the powdered from the granular material. by

carryin away the powdered material in a which consists in comminuting the phos-- phate bearing material to reduce the clay to an inrpalpa le powder, separating the owere c ay from the remaining material; rther comminutin the remaming material to reduce the low content plhosphate to an impalpable powder and the igh content phosphate to granular form, and then separating the powdered low content phosplfiate from the granular'high content phosp ate. a v

4..Method of separating phosphate rock from clay which consists in sub ecting the phosphate bearing material, in a dry state, to a comminuting operation which reduces the'clay to a finer state of subdivision than the rock, and subjecting the comminuted material to an air separation which removes the clay from the rock.

5. Method of separating phosphate rock having-a high hos hate q ntent from rock having a low p osp late content, which consists in subjecting the rock while in a dry state to a comminuting operation which'reduces the low content rock to a finer state of subdivision than the rock having a high 1 phosphate content,"and subjecting the comminuted materialto air air-separation which removes the more finely divided material a from that less finely divided.

6. Method of separating phosphate rock having a relatively high percentage of tricalcium phosphate from clay and from a lower content phosphate rock which consists incomminuting the material to reduce the cla to a finer state of subdivision than the roc making an air separation of the clay from the rock, subjecting the rock to a second comminuting operation to reduce the softer low content rock to a finer state of subdivision than the hlgh content rock,

' and removing the finer particles from the rest of the material by an air separation.

7. Method of separating phosphate rock having a relatively high percentage of tricalcium phosphate from clay and from a lower content phosphate rock which consists in comminuting the material by a beating operation to reduce the clay to an -im-' palpable power and to break up the rock, removing the powder from the rock by an air phate rock having a lower p osphate content 6 which consists in subjecting the material to a beating operation to pulverize the clay and to a grinding operation to pulverize the softer low content rock and separating the pulverized material from the rest, while the 7 material is in a dry state. 9. Method of treating phosphate -bearing material which consists in comminuting the material to reduce the clay in the same to a pulverized state and to breakup the harder constituents but to a less finely divided state. and subjecting the material in a dry state to an air separation for removing the powdered clay from the phosphate. 7

10. Method of treating phosphate bearing 80 material which consistsin comminuting the material to reduce the low-grade phos hate in the same to a pulverized state and t0 reak up the high grade phosphate in the material but to a less finel divided state and sub- 35 jecting the material in a dry state to a separating o eration to remove the pulverized materia from the rest.

11. Method of separating phosphate from clay which'consists in subjecting the phos l0 phate bearing material to a beating operation which powders the clay and breaks up the phosphate but in a less finely divided state, and separating the phosphate from the clay while the material is in a dry state.

i 12. Method of separating phosphate rock from other substances with which it is associated in nature, which consists in subjecting the material to a comminuting operation that reduces said other substances to a finer state than the phosphate rock, then separating the phosphate rock from-the other substances with the material in a dry state.

13. Method of separating phosphate-rock from other substances with which it is'asso- 'ciated in-nature, which consists in subject- SAMUEL B. KANOWITZ. HYLEMAN.A. WEBSTER. 

